DE2713456A1 - METHOD OF MANUFACTURING HYDROPHILIC FIBERS - Google Patents

Description

Bayer Aktiengesellschaft

Central area of patents, trademarks and licenses

5090 Leverkusen, Bayerwerk Dn / bc

March 25, 1977

Process for the production of hydrophilic fibers

It has already been proposed to produce hydrophilic threads and fibers from thread-forming synthetic polymers, by adding 5 to 50% by weight, based on solvent and solids, of a substance to the spinning solvent adds, which is essentially a nonsolvent for the polymer and has a higher boiling point has as the solvent used and the one with the spinning solvent and one as the washing liquid for the Threads suitable liquid is well miscible and then this nonsolvent from the threads produced washes out again. Preferred nonsolvents in this process are polyhydric alcohols such as glycerol, sugar and glycols.

Such fibers, e.g. spun from acrylonitrile polymers, have a core-sheath structure and a Water retention capacity of at least 10%. The higher the weight fraction of added nonsolvent, the more the hydrophilicity of the threads increases.

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It has now surprisingly been found that such hydrophilic threads and fibers can also be obtained if the threads are used with steam or before they are solidified brings it into contact with the vapor of another liquid which coagulates the filaments and thereby solidifies them.

The invention therefore relates to a process for the production of hydrophilic threads and fibers from thread-forming synthetic polymers by spinning a polymer solution according to a dry spinning process, characterized in that the threads are immediately after exiting the nozzle, but at the latest at a point in time when the thread consolidation has not yet occurred is complete, with water vapor or the vapor of another liquid that coagulates the filaments. According to the process according to the invention, polymers which are normally not hydrophilic, preferably acrylonitrile polymers and particularly preferably those with at least 50% by weight, in particular with at least 85% by weight, of acrylonitrile units are spun.

The method according to the invention can also be used for the production of bicomponent or modacrylic fibers, fibers from homopolymers, spun-dyed fibers or also fibers made from polymer blends, e.g. from mixtures of acrylonitrile polymers and polycarbonates. Likewise let linear, aromatic polyamides such as the polyamide from m-phenylenediamine and isophthalic acid or those which optionally also have heterocyclic ring systems, such as benzimidazoles, oxazoles or thiazoles and which can be produced by a dry spinning process from a spinning solution with a solvent to be evaporated are, use according to the invention.

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Further suitable compounds are polymers with melting points above 300 ^° C., which in general can no longer be spun from the melt and are produced by a solution spinning process, for example by dry spinning.

The spinning process is in principle a conventional dry spinning process, preferably from strongly polar organic solvents such as dimethylformamide, dimethylacetamide and dimethyl sulfoxide. However, mixtures can also be used made of polymers, spinning solvents and nonsolvents for that Polymers such as water, polyhydric alcohols and glycols that combine with the spinning solvent to form a Let the solution mix, be spun.

According to the invention suitable vapors for coagulating the still Non-solidified threads are, besides water vapor, all vapors of substances ^ which are necessary for the spun polymers, in particular acrylonitrile polymers represent a nonsolvent, such as, for example, in the case of acrylonitrile polymers mono- and polysubstituted alkyl ethers and esters of polyhydric alcohols, such as diethylene glycol, Triethylene glycol, tripropylene glycol, triethylene glycol diacetate, tetraethylene glycol, glycol ether acetates. Furthermore, alcohols such as 2-Ethy! Cyclohexanol, glycerine, Esters or ketones or mixtures, e.g. from ethylene glycol acetates, suitable. In addition to haters, those substances that can be easily evaporated are particularly preferred, their The flash point is high and the flammability is low, for example methylene chloride and carbon tetrachloride.

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Depending on the location and intensity of the steam injection onto the polymer threads, as well as the thermal conditions in the spinning shaft, both the cross-sectional structure and the width of the surface area and the hydrophilicity of the threads can be controlled. It has been found that core-sheath fibers with round to circular cross-sectional shapes and a very thin outer surface of a maximum of approx. 25% of the total cross-sectional area and an extremely high water retention value of approx. 60% and more are obtained when the spinning is carried out at low shaft temperatures from a maximum of 140 ° C., preferably from 20 to 120 ^° C. (cf. Table I, No. 1 to 3).

At higher shaft temperatures, preferably above 160 ° C, core sheath fibers with oval to triobal cross-sectional shapes and water retention values of approx. 20 to 60% are obtained, whereby the surface area can make up approx. 60% of the total cross-sectional area.

The thickness and thus the edge width of the lateral surface can be determined according to the invention by the choice of the ratio of Control air to steam mixture in such a way that core sheath fibers are preferred for high steam and low air volumes with a large seam width of the outer surface, which can make up up to 75% of the total fiber cross-sectional area, can be generated (see Table I, No. 21).

Conversely, if only little steam is used in relation to the amount of air in the spinning process, core sheath fibers are obtained which are approaching more and more the dumbbell shape customary in the dry spinning process and which are correspondingly low Have water retention capacity (see Table I, No. 5 and 6).

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The cross-sectional structure of the core sheath fibers was based on determined by electron micrographs. For the determination of the core or surface area of the fibers 100 fiber cross-sections were determined by quantitative analysis with the "Classimat" image analyzer Leitz company evaluated.

In the method according to the invention, preference is given to steam blown in above the spinneret in the direction of the air flow and the thread take-off. It is, however, an exhilaration Transverse to the threads also possible below the nozzle, if the blowing is done in such a way that there is no excessive turbulence occurs.

In order to avoid excessive condensation of water vapor and solvent mixtures in the spinning shaft, a shaft temperature of over 100 ° C., preferably 105 to 140 ° C., with the shortest possible shaft lengths, for example 1 m in length, has proven to be optimal. As already mentioned, the width of the outer surface and the porosity can be controlled depending on the intensity of the steam injection, ie this makes it easy to determine the degree of matting and the dyeability of the spun threads as desired for the later application.

In principle, the nonsolvent vapors, preferably water vapor, preferably saturated steam, can be brought into action as long as the thread material is not yet completely solidified.

The method according to the invention can therefore also advantageously be carried out by the action of steam by means of a

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Nozzle or a pipe immediately after the thread sheet has left the spinning shaft. Here too arise hydrophilic, porous core sheath fibers.

According to the method according to the invention, the steam injection In the spinning chute, steam-air mixtures are preferred because they are controlled by the temperature let that no noticeable condensation takes place in the spinning shaft. When spinning in a pure steam atmosphere very strongly matted threads are obtained, while in the case of steam-air mixtures shiny threads of high hydrophilicity can also be produced. With superheated steam, the invention However, not achieving goals. The required amounts of steam and air are based naturally according to the specified shaft dimensions and the respective process parameters such as spinning speed, Spinning temperature, shaft temperature, solution concentration, etc. as well as the desired thread properties. The coordination of these conditions can be carried out in individual cases by means of appropriate preliminary tests.

When working with a spinning shaft with a length of 600 cm and a diameter of 5 cm, the following results were obtained shown:

If the amount of air during spinning is reduced below a critical amount, the gas volume present is at low amounts of steam so small that the polymer solution is no longer spinnable. The lower limit of spinnability is around 2 cbm of air per hour per kg of spun material with a minimum amount of steam of 1 kg per hour (cf. Table I, No. 22).

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The minimum amount of injected water vapor required is, in order to still produce hydrophilic core sheath fibers, is approx. 1 kg per 1 kg of spun material at a shaft temperature of 20 ° C, if one assumes a normal polyacrylonitrile spinning solution with a concentration of ^ o%.

However, if you use a mixture of polymers ^ spinning solvents and nonsolvents, even small amounts of steam of 0.1 kg per kg of spun material are sufficient in order to considerably increase the water retention capacity of such core sheath fibers (cf. Example III, b and c).

At higher temperatures shaft, especially above 16O ⁰ C, a larger amount of steam, preferably about 10 kg of steam per hour per kg of spun material, is required.

If the steam is only applied to the threads outside the spinning shaft, for example with a nozzle, then in Usually 5 kg of steam per hour and per kg of spun material is sufficient to obtain hydrophilic, porous core sheath threads.

The following examples serve to further illustrate the invention. Parts and percentages relate if not otherwise noted, on weight.

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example 1

-β-

An acrylonitrile copolymer of 93.6% of acrylonitrile, 5.7% methyl acrylate and 0.7% of sodium with a K value of 81 was dissolved in dimethylformamide (DMF) at 80 ⁰ C. The filtered spinning solution, which had a final concentration of approx. 30% by weight, was dry-spun from a 180-hole nozzle. 25 kg of saturated steam per hour and 10 cbm of air at 150 ° C. per hour were blown into the spinning shaft (length 600 cm, 50 cm) above the nozzle. The duct temperature was 140 ⁰ C. Per kg of spun material created were about 5.8 kg of steam consumed. The DMF content of the threads was 59%, based on the polymer solids. The threads with a total titer of 2400 dtex were collected on bobbins and brought together to form a cable of 684 * 00 dtex. The fiber tow was then stretched 1: 4.0 times in boiling water, washed, provided with an antistatic preparation, ^{dried at 120 °} C. with a 20% shrinkage allowance, crimped and cut into staple fibers 60 mm in length. The individual fibers with a final denier of 3.3 dtex had a water retention capacity according to DIN 53814 of 63%. The fibers had a pronounced kernmantle structure with an oval cross-sectional shape. The surface area of the jacket was approx. 45% of the total cross-sectional area.

Further examples are given in Table I below. The spinning solutions were as described in Example 1 to Core sheath fibers with a final denier of 3.3 dtex spun and post-treated. The amount of steam and air as well as the air and duct temperature were varied during the spinning process. The polymer described above was used as the solid.

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tr ¹ φ

Cn

Table I.

OO

co co co co

cn ar>

No. Tarpfrner.ge Air vent Air terp. Shaft-ip. Lookout. Cross-sectional ? proportion of Γ «? - salary WR (after ■ 45 In kg per (visual forra I-'ar.tel area DIN 53S14 45 kg Splnr-sut (cWh) ⁰ C ° C Judgement) v. Gcsantt- Spinning material % in*) 42 cross-sectional 48 1 2.8 10 150 20th matted Circular 8th 79 118 58 2 2.8 10 150 100 matted Circular 12th 59 π 3 2.8 10 150 120 patters Circular 25th 56 65 53 4th 2.8 10 150 140 glittering oval 35 41 59 62 5 2.8 10 150 160 glittering dumbbell 70 33 12th 6th 2.8 10 150 200 glittering Square 95 21 8th 7th 2.8 10 40 140 shiny up Around 40 41 44 matted 8th 2.8 10 100 140 glittering oval 35 46 9 2.8 10 120 140 glittering oval 35 47 10 2.8 10 200 140 glittering Round to oval 35 46 11 4.6 140 patters Around 65 48 12th 4.6 5 150 140 matted Oval to 50 59 Trilflbal υ 4.6 10 150 140 glittering Circular 30th 58 14th 4.6 20th 150 lAO glittering Circular 25th 53

1 C

Table I (continued)

O CO I co co co

Kr. council> fr «ense Air force Air terrp. Schachtterp. Appearance Qi: sectional * Proportion of Dr-T salary W-Λ (calc i ir. kg per (visually· fortn Outer surface DIN 55814 kg of pinned material (cWh) ⁰ C ° C Bulging) v. Total Spinning material % in 55) cross-section 15th 0.3 10 150 1 * 0 dumbbell 1 31 4th 16 0.7 10 150 1 * 0 shine dumbbell 1 33 9 17th 1.* 10 150 m © g.l ¥ n? 6ixi Angular to 20th 56 61 Trü * b * l 18th 2.8 10 150 140 gliü.zend oval 35 41 59 19th 5.6 10 150 140 shiny up Circular 40 43 65 mattlort 20th 8.6 10 150 140 nnttlert Circular 60 64 72 21 13.8 10 150 140 wt * .f: ert Circular 75 73 69 22nd 0 # 2 150 140 Keire thread pre-consolidation

As can be seen from the table, there are clear relationships between the cross-sectional shape and the jacket width as well as in the water retention capacity and in the appearance of the porous core sheath fibers.

One (1 no. To 3) matted fibers of high hydrophilicity is obtained, usually with a circular cross section and thinner lateral surface below 30% of the total cross-sectional area at temperatures below chute 140 ⁰ C, preferably at 20 to 120 ° C. With increasing shaft temperatures, the water retention capacity decreases sharply, the threads become shiny and turn into the dumbbell shape at approx. 160 ° C (No. 4 to 6).

Matted threads with mostly round cross-sections, but thicker sheath widths from approx. 40% of the total cross-sectional area, also arise with low air volumes and air temperatures (No. 12 and 7), with high steam quantities from approx. 5 kg steam per kg spun material (No. 19 to 21), as well as with Spinning in a pure steam atmosphere (No. 11).

Shiny fibers with water retention values above 10% are preferably obtained at duct temperatures above 120 ° C (No. 4 and 5), at air temperatures from 100 ° C (No. 8 to 10), with air volumes above 5 cbm per hour, preferably from 10 cbm (No. 13 and 14), as well as for steam quantities below 5 kg of steam per kg of spun material (No. 17 and 18).

At amounts of steam below 1 kg per kg of spun material, how Examples Nos. 15 and 16 from Table I show that sufficient hydrophilicity is no longer produced. Own the fibers the dumbbell shape typical of the dry spinning process.

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Example 2

64 kg of dimethylformamide were mixed with 4 kg of water in a kettle at room temperature. Subsequently were 32 kg of an acrylonitrile copolymer having the chemical composition from Example 1 were metered in with stirring. The suspension, which has a polymer solids content of 32 % By weight was fed to a heating device via a gear pump and heated to 130.degree. The dwell time in the heating device was 3 minutes. The spinning solution was then filtered and directly one 380 hole nozzle supplied. 10 kg of saturated steam per hour and 40 cbm of air were fed into the spinning shaft above the nozzle blown in at 120 ° C per hour. The shaft temperature was 140 C. Per kg of spun material produced was approx. 1.75 kg Steam used up. The DMF content of the threads was 51%, based on the polymer solids. The threads of the total titer 3800 dtex were collected on spools and combined to form a cable of 478,800 dtex and as in Example 1 described after-treated to fibers with a final denier of 3.3 dtex. The fibers had a water retention capacity of 33%. They had a pronounced kernmantle structure with a bean-shaped to triobal cross-sectional shape. The area share of the jacket was approx. 15% of the total cross-sectional area .

Example 3

a) 60 kg of DMF were mixed with 10 kg of glycerol in a kettle at room temperature. Then 30 kg became one Acrylonitrile copolymer of the chemical composition from Example 1 is metered in with stirring.

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The suspension was dissolved as described in Example 1, filtered and from a 380 hole nozzle under analogous Dry spun in steam and air conditions. Approx. 1.9 kg of steam were used per kg of spun material produced. The DMF content of the threads was 54%, based on the polymer solids. The threads with a total denier of 3560 dtex were plied again to form a cable and, as set out in Example 1, to fibers with a final denier of 3.3 dtex post-treated. The fibers had a water retention capacity of 74%. They had a pronounced kernmantle structure from oval to bean-shaped cross-sectional shape. The surface area of the jacket was approx. 20% of the total cross-sectional area.

b) 0.1 kg of steam per kg of spun material in the spinning direction were added to part of the spinning solution after the nozzle exited the shaft blown. The threads with a total denier of 3560 dtex were again analogous to fibers with a final denier of 3.3 dtex post-treated. The fibers had a water retention capacity of 36%.

Example 4

60 kg of DMF were mixed with 5 kg of tripropylene glycol in a kettle at room temperature. Then were 35 kg an acrylonitrile copolymer of the chemical composition from Example 1 is metered in with stirring and dissolved as described in Example 2, filtered and dry-spun from a 72 hole nozzle. In the spinning shaft were above the nozzle 12 kg of methylene chloride vapors per

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Hour and 10 cbm of air at 40 ° C per hour blown in. The shaft temperature was 24 ° C. Per kg of spun material produced 6.2 kg of methylene chloride vapor were consumed. The DMF content of the threads was 76%, based on the polymer solids. The threads with a total titer of 1620 dtex were again collected on bobbins, plied and as described in Example 1 aftertreated to fibers with a final denier of 6.7 dtex. The fibers had a water retention capacity of 102%. They had a pronounced kernmantle structure with a circular cross-sectional shape. The area proportion of the mantle was approx. 5% of the total cross-sectional area.

Example 5

The spinning solution of an acrylonitrile copolymer of the same composition and concentration as described in Example 1 was dry-spun from a 180 hole nozzle. 20 cbm of air at 50 ° C. per hour were blown in. The shaft temperature was 120 ° C. The DMF content of the threads was 41%, based on polymer solids. The threads with a total denier of 2400 dtex were sprayed with 60 kg of saturated steam per hour from a nozzle in the direction of the spinning take-off immediately after leaving the spinning shaft. The nozzle was in a box with a condensate drain. The steam consumption was approx. 13.9 kg of steam per kg of spun material produced. The threads were then wound up, plied to a cable with a total denier of 684 ¹ 000 dtex and aftertreated as set out in Example 1 to give fibers with a final denier of 3.3 dtex. The fibers had a water retention capacity of 34%. They had a kernmantle structure with a bean-shaped to oval cross-sectional shape. The surface area of the jacket was approx. 20% of the total cross-sectional area.

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Example 6

a) The spinning solution of an acrylonitrile copolymer of the same composition and concentration as described in Example 2 was dry spun from a 380 hole nozzle. 10 kg of saturated steam were poured into the spinning shaft per hour, but no air, above the spinneret blown in. The shaft temperature was 88 ° C. Approx. 1.75 kg of steam was consumed per kg of spun material produced. The DMF content of the threads was 46%, based on the polymer solids. The threads with a total denier of 3800 dtex were collected on bobbins, plied to a cable and as described in Example 1 to fibers of the final denier 3.3 dtex aftertreated. The water retention capacity of the threads was 119%. They again had a kernmantle structure with oval to round cross-sectional shape. The surface area of the jacket was approx. 30% of the total Cross sectional area. The fibers were heavily matted.

b) A spinning solution of the same composition and concentration was spun in the same way. Instead of 10 kg of saturated steam, 37 kg of saturated steam per hour were fed into the shaft blown in above the nozzle. 6.5 kg of steam were used per kg of spun material produced. The DMF content of the Threads was 70% based on polymer solids. the Threads were aftertreated analogously to fibers with a final denier of 3.3 dtex. The water retention capacity of the fibers was 131%. The fibers again had a core sheath structure and were heavily matted with an oval to round cross-sectional shape. The surface area of the jacket was approx.

50% of the total cross-sectional area.

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Example 7

5.3 kg of an acrylonitrile copolymer of 93.6% of acrylonitrile, 5.7% methyl acrylate and 0.7% Natriununethallylsulfonat were dissolved at 90 ⁰ C in 13.6 kg of DMF. In addition, 5.3 kg of a polymer mixture consisting of 4.5 kg of acrylonitrile homopolymer and 0.8 kg of an acrylonitrile copolymer composed of 91% acrylonitrile, 5.6% methyl acrylate and 3.4% sodium methyl sulfonate were dissolved in 16.3 kg DMF at 100.degree. Both solutions were fed to a bifilar nozzle in a ratio of 1: 1 and spun side by side. 10 kg of saturated steam per hour and 10 cbm of air at 150 ° C. per hour were blown into the spinning shaft above the nozzle. The shaft temperature was 140 ° C. Approx. 2.4 kg of steam were consumed per kg of spun material produced. The threads were combined to form a cable, drawn 1: 3.6 in boiling water, washed, prepared and dried under tension at 110 ° C., crimped, cut and fixed in steam for 1.5 minutes. The fibers, which had a single titer of 3.3 dtex, had a water retention capacity of 54%. They had a pronounced kernmantle structure with a mushroom-shaped cross-section. The area proportion of the jacket was approx. 50% of the total cross-sectional area. The fibers had about 11 curl arcs per cm and a curl of 10.2%. The crimp was permanent and remained almost unchanged when treated with water up to the boiling temperature.

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Example 8

a) Part of the spinning solution from Example 6 was at a shaft temperature of 200 C instead of 88 ° C below otherwise spun under analogous conditions and aftertreated to fibers with a final denier of 3.3 dtex. The fibers had a Water retention capacity of 24%. They in turn had a kernmantle structure ranging from triobal to T-shaped Cross-sectional shape. The area proportion of the jacket was less than 5% of the total cross-sectional area.

b) If the spinning was carried out at a shaft temperature of 140 ° C under otherwise constant conditions, in this way, core sheath fibers with an oval to triobal cross-sectional shape were obtained. The proportion of the surface area was approx. 30% of the total cross-sectional area and the water retention capacity of the fibers was 49%.

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Claims (4)

Claims 1) Process for the production of hydrophilic threads or fibers from thread-forming synthetic polymers by Spinning a polymer solution according to a dry spinning process, characterized in that the threads are directly after exiting the spinneret, but at the latest at a point in time when the thread consolidation is still occurring is not complete, with water vapor or the vapor of another liquid that coagulates the filaments in Brings touch. 2) Method according to claim 1, characterized in that the polymer is an acrylonitrile polymer. 3) Method according to claim 2, characterized in that the acrylonitrile polymer consists of at least 50% by weight Consists of acrylonitrile units. 4) Process according to claims 1 to 3, characterized in that the steam in the spinning shaft above blows in the nozzle in the direction of spinning. Le A 17 956 - 18 - 809839/0568 ORIGINAL INSPECTED